CONCORD, N.C. — Kurt Busch will have the eyes of the motorsports world on him on the biggest motorsports day of the year Sunday.

He will have the interest of fellow racers, some admiring him and others wondering why he would want to put himself through both the Indianapolis 500 and Coca-Cola 600 on the same day, possibly racing 1,100 miles in less than 12 hours.

He has piqued the curiosity of fans, who love it when drivers cross over from different racing disciplines. They will follow not only his races on the track, but his race from Indianapolis Motor Speedway to Charlotte Motor Speedway as he tries to make it for the start of the Coca-Cola 600.

This will be his day.

“He’s representing the entire sport,” said Dale Earnhardt Jr., NASCAR’s most popular driver. “Whether he knows it or not, he’s got a lot of people, drivers, crews and just about everyone in the infield pulling for him to do well because he is representing all of us.

“He’s definitely put in a strong effort to make a different impression. I have to hand it to him. He’s done a lot of work.”

Busch will begin the day starting 12th at Indianapolis Motor Speedway, where his only race experience is in a car that weighs 1,730 more pounds and has 500 pounds less downforce but with similar horsepower.

The 2004 NASCAR Cup champion has never competed in an IndyCar race. The three other drivers who have done the double — John Andretti, Tony Stewart and Robby Gordon — all had IndyCar roots. Only Stewart in 2001 completed all 1,100 miles, finishing sixth at Indy and third at Charlotte.

“It’s a tough car to drive, just like a Sprint Cup car is tough to drive,” Busch said. “It hasn’t been overwhelming, but at the same time each day in the Indy car, I’m a student and I’m learning.

“How many times have we all told ourselves if I would have known now what I could have known then? The way to approach this is to have fun. I have zero IndyCar experience and I’m trying to elevate my game over there to be competitive.”

He has impressed the open-wheel world with his performance. Yes, he crashed Monday in practice but he had gotten up to speed quickly and qualified 12th despite having to rush back to Charlotte for the Sprint All-Star Race last week.

“He is talented and incredibly brave,” said former Indy 500 winner and team owner Eddie Cheever. “If he digests this last hit he had, it took me a long time to digest, if he can go through that (and) he's in that leading group at the end of the race, I would consider him a possible top-three finisher. … He’s been incredible. I'm very impressed.”

Busch said he is running the Indy 500 in part to add a spark to the motorsports world, in addition to pegging the fun meter for a racer. He has gotten a warm reception from the Indy fan base. Whether that means more focus for NASCAR remains to be seen.

“It has to bring some interest just from a standpoint that it’s a big challenge from both worlds,” said Busch’s Stewart-Haas Racing teammate Kevin Harvick. “Whether it’s coming over here and just racing this race or just going over there.

“They are huge races. I think it’s good for both series that he is doing it, bringing a lot of attention both ways.”

Some drivers in the NASCAR garage are curious, others are envious and others think it’s cool, though they would never try it.

“That doesn’t look one iota of fun at all,” Clint Bowyer said about watching Busch wreck in an Indy car. “That was a hard hit and just from looking at it, those things blow apart and you see us wreck and it kind of flat sides the right side and you’re like, ‘You’ll be OK.’

“You see them things blow apart and you’re like, ‘Man, is he even going to get out?’ No, it doesn’t look like fun, but it’s fun to watch.”

Six-time Sprint Cup champion Jimmie Johnson never was able to make the Indianapolis 500 work in conjunction with his Cup sponsors. Once he started a family, he promised his wife he wouldn’t compete in an Indy car.

One of NASCAR's most physically fit drivers, Johnson has given Busch advice on nutrition and hydration. He believes Busch’s biggest challenge won’t necessarily be driving the car.

“Stress takes a big toll on the body,” Johnson said. “You're stressed about your balance and your setup for your stock car. You're stressed about your balance and setup for your Indy car. Practice sessions. Are you eating, drinking, getting enough rest? Media obligations. On Sunday, is it going to affect the IndyCar race. Is the helicopter or plane on time?

“We all know what (stress) does to our system. It wears you down pretty quick. … He's got a lot of stress on his plate right now.”

Busch’s biggest stress might be his “day job” as he will have to start from the rear of the field for the Coca-Cola 600 because he will miss the prerace drivers meeting. His team has yet to find a consistent balance to get him comfortable on intermediate tracks this year.

“As each day gets closer, you're getting more anxious to get it done because you've been preparing for so long, then experiencing so many new things,” Busch said. “I'm the least prepared of the individuals who have done the double. They've all come from the open-wheel world and settled into the NASCAR world.

“For me, the lack of experience in the IndyCar world is what makes this fun, exciting, challenging. At the end of the day it's just about giving it my best and not making a mistake on Sunday to try to get 1,100 miles in.”

The stress also could include the eyes of his peers on him. As Earnhardt said, Busch has the respect of the garage not just for his racing ability but also because of his commitment to use the double to promote awareness for health issues of military veterans, the mission of the Armed Forces Foundation where his girlfriend, Patricia Driscoll, serves as executive director.

“I respect him a lot more because of that,” said Earnhardt, who is sponsored by the National Guard. “The racing thing, hell, we all like to race so I can understand his enjoyment of doing the Indy deal. I can’t wait to watch and pull for him.”